The group O.A.R. (Of a Revolution) -- recent entries into the industry's mainstream after enjoying a loyal following on the college scene -- performed a two-song set on the infield in between the All-Star Futures Game and the Legends and Celebrity Softball Game on Sunday night.
Irlbacher, 20, didn't know the concert was part of the deal when he bought his tickets for Sunday, but he wasn't about to complain.
"It was definitely pretty cool," he said. "They're not the usual poppy band with their sounds. They're just a good band."
Count Eric Treisenderfer, 16, though, on the other side. He was part of the near sellout crowd partly because of the band's showing, which included a performance of their hit, "Love and Memories."
"I was happy that I came," he said. "I like that skull kind of music."
The quintet of O.A.R., together since high school and their days at Ohio State, has sold more than a million albums since coming onto the scene eight years ago with their unique, reggae-meets-rock sound.
David Briggs is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.